Regeneration Model
Introduction
Forest regeneration models are difficult. There are good models out there but they work well for certain forests, species and silviculture. This project is to locate well respected and documented forest regeneration models that can be implemented in Assisi Forest. Anyone interested in regeneration modeling is welcome to join the discussion.
About Assisi Models
Current Assisi Regen Models
Currently only the FVS sprout model has been implemented. Other regeneration response such as seedlings are not automatic: then must must be scheduled through Planting actions. FVS small tree growth models have also been implemented in Assisi.
Which Model to Implement?
As always, existing models are the starting point. Assisi is a "user" of models, not a "designer" of models. The first task is finding existing models that are documented well enough to implement. Having source code is best which can mean using public models such as FVS or private models under NDA.
Assisi Approach to Implementing Models
Assisi prefers to code models that others use and maintain. This is because the science of models is an ongoing research process that is best maintained by research groups. If coding a model for a research group speeds up the use of a model then Assisi is more than happy to help. The only requirement is that the code must work with Assisi Forest. Usually a FORTRAN or C++ DLL with well designed API is sufficient. ACADIA, ORGANON and Flewelling DLLs are all examples of models with widely usable API interfaces. Another option is to code a model as external script where the model functions and options are user programmable using C# script. Assisi Action Triggers are implemented this way to allow complex logic trees coded by users of Assisi Forest to be used. Under any approach, as many options and coefficients for a model will be exposed as possible.
Regen Models
FVS Sprout Model
Specifically for root or stump sprouting. Part of what is called the Partial Establishment Model in FVS. Available in all FVS variants.
The FVS Sprout model for the Lake States has been implemented in Assisi.
FVS Seedling Model
FVS's natural response model is called the Full Establishment Model. It adds automatic seedling response to disturbance. This model has only been calibrated to some western variants.
The model includes 4 site prep types: None, Mechanical, Burn and Road. (What is "road"?) Seedling response is divided into Advance, Subsequent and Excess cohorts. Establishment is modeled by choosing the best survivors from a cohort of probable seedlings.
The FVS framework may be robust and studied enough to extend beyond its current variants. But if there isn't enough data to calibrate, then either it wont be used or can be used but only with best guess coefficients. Still, implementing it now and finding out what calibration would require might be wise enough.
REGEN3
REGEN3 is an expert system type of regen response model. Description of silviculture is used to navigate a decision tree of regeneration response. (I think. I haven't seen the source code.) The decision trees are user modifiable and organized into a library so that local expert knowledge can become a part of model logic.